This document provides standards for reference radiographs used to evaluate steel castings up to 2 inches thick. It includes: 1. An overview of the scope and purpose of the reference radiographs, which illustrate various types and severity levels of discontinuities commonly found in steel castings. 2. Descriptions of the categories and types of discontinuities represented, including gas porosity, inclusions, shrinkage, cracks, tears, and mottling. The discontinuities are graded on a scale of 1 to 5 based on their quantity, size, and distribution. 3. Procedures for how to use the reference radiographs to evaluate production radiographs and determine whether castings meet specified radi

1. Designation: E446 − 14
Standard Reference Radiographs for
Steel Castings Up to 2 in. (50.8 mm) in Thickness1
This standard is issued under the fixed designation E446; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 These reference radiographs2
illustrate various
categories, types, and severity levels of discontinuities occur-
ring in steel castings that have section thicknesses up to 2 in.
(50.8 mm) (see Note 2). The reference radiograph films are an
adjunct to this standard and must be purchased separately from
ASTM International, if needed (see 2.2). Categories and
severity levels for each discontinuity type represented by these
reference radiographs are described in 1.3.
NOTE 1—The basis of application for these reference radiographs
requires a prior purchaser supplier agreement of radiographic examination
attributes and classification criterion as described in Sections 4, 6, and 7
of this standard.
NOTE 2—Reference radiographs previously used for this thickness
range carried the designation E71, but included a now rarely used gamma
source, that is, radium. The current document is also updated by inclusion
of several recognized shrinkage or C categories and by elimination of the
crack and hot tear categories except for one example of each of these
discontinuity types. Reference radiographs for thicker sections may be
found in Reference Radiograph standards E186 and E280. Reference
Radiograph standards E446 and E186 provide some overlap of severity
levels for similar discontinuity categories within the same energy level
range (see 4.2, 5.1, and 6.3).
1.2 These film reference radiographs are not intended to
illustrate the types and degrees of discontinuities found in steel
castings when performing digital radiography. If performing
digital radiography of steel castings up to 2 in. (50.8 mm) in
thickness, refer to Digital Reference Image Standard E2868.
1.3 These reference radiographs consist of three separate
volumes (see Note 3) as follows: (I) medium voltage (nominal
250-kV) X rays. (II) 1-MV X rays and Iridium-192 radiation,
and (III) 2-MV to 4-MV X rays and cobalt-60 radiation. Unless
otherwise specified in a purchaser supplier agreement (see 1.1),
each volume is for comparison only with production radio-
graphs produced with radiation energy levels within the thick-
ness range covered by this standard. Each volume consists of
six categories of graded discontinuities of increasing severity
level and four categories of ungraded discontinuities. Refer-
ence radiographs containing ungraded discontinuities are pro-
vided as a guide for recognition of a specific casting disconti-
nuity type where severity levels are not needed. Following is a
list of discontinuity categories, types and severity levels for the
adjunct reference radiographs of this standard:
1.3.1 Category A—Gas porosity; severity levels 1 through 5.
1.3.2 Category B—Sand and slag inclusions; severity levels
1 through 5.
1.3.3 Category C—Shrinkage; 4 types:
1.3.3.1 Ca—linear shrinkage—Severity levels 1 through 5.
1.3.3.2 Cb—feathery shrinkage—Severity levels 1 through
5.
1.3.3.3 Cc—sponge shrinkage—Severity levels 1 through 5.
1.3.3.4 Cd—combinations of linear, feathery and sponge
shrinkage—Severity levels 1 through 5.
1.3.4 Category D—Crack; 1 illustration.
1.3.5 Category E—Hot tear; 1 illustration.
1.3.6 Category F—Insert; 1 illustration.
1.3.7 Category G—Mottling; 1 illustration.
NOTE 3—The reference radiographs consist of the following:
Volume I: Medium Voltage (nominal 250 kVp) X-Ray Reference
Radiographs—set of 34 illustrations (nominal 5 by 7 in.) in a 15 by 17-in.
ring binder.
Volume II: 1-MV X Rays and Iridium-192 Reference Radiographs—Set
of 34 illustrations (nominal 5 by 7 in.) in a 15 by 17-in. ring binder.
Volume III: 2-MV to 4-MV X Rays and Cobalt-60 Reference
Radiographs—Set of 34 illustrations (nominal 5 by 7 in.) in a 15 by 17-in.
ring binder.
NOTE 4—Although Category G–Mottling is listed for all three volumes,
the appearance of mottling is dependent on the level of radiation energy.
Mottling appears reasonably prominent in Volume I; however, because of
the higher radiation energy levels mottling may not be apparent in Volume
II nor Volume III.
1.4 The values stated in inch-pound units are to be regarded
as the standard. SI values are shown for information only.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1
These reference radiographs are under the jurisdiction of ASTM Committee
E07 on Nondestructive Testing and are the direct responsibility of Subcommittee
E07.02 on Reference Radiological Images.
Current edition approved Oct. 1, 2014. Published October 2014. Originally
approved in 1972. Last previous edition approved in 2010 as E446 – 10. DOI:
10.1520/E0446-14.
2
For ASME Boiler and Pressure Vessel Code applications see related Reference
Radiographs SE-446 in Section V of that Code.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2. 2. Referenced Documents
2.1 ASTM Standards:3
E94 Guide for Radiographic Examination
E186 Reference Radiographs for Heavy-Walled (2 to 41⁄2-in.
(50.8 to 114-mm)) Steel Castings
E242 Reference Radiographs for Appearances of Radio-
graphic Images as Certain Parameters are Changed
E280 Reference Radiographs for Heavy-Walled (41⁄2 to 12-
in. (114 to 305-mm)) Steel Castings
E1316 Terminology for Nondestructive Examinations
E2868 Digital Reference Images for Steel Castings up to 2
in. (50.8 mm) in Thickness
2.2 ASTM Adjuncts:4
Reference Radiographs for Steel Castings Up to 2 in. (50.8
mm) in Thickness:
Volume I, Medium Voltage (Nominal 250 kVp) X-Rays5
Volume II, 1-MV X-Rays and Iridium-1926
Volume III, 2-MV to 4-MV X-Rays and Cobalt-607
3. Terminology
3.1 Definitions—For definitions of terms relating to radio-
graphic examination, see Terminology E1316.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 production radiograph—a radiograph under review
for compliance with this standard.
3.2.2 discontinuity type—a specific discontinuity character-
ized by its cause and appearance. For example: linear shrink-
age is a specific discontinuity type.
3.2.3 discontinuity category—a nomenclature system used
for grouping discontinuity types. For example: linear shrinkage
is assigned category “Ca” where “C” represents the general
shrinkage category and “a” represents the specific linear
shrinkage discontinuity type.
3.2.4 discontinuity severity level—a relative rank in terms of
“quantity, size and distribution” of a collection of discontinui-
ties where “1” is the least and “5” is the greatest “quantity, size
and distribution” present on the reference radiograph. Ex-
ample: a severity level of “1” is more restrictive (requires a
higher level of workmanship fabrication quality) than a sever-
ity level of “2”.
3.2.5 discontinuity class—an assigned workmanship fabri-
cation quality rating characterized by a discontinuity type,
category and severity level. For example: “Ca 2” is a discon-
tinuity class comprised of linear shrinkage with a severity level
of “2”.
3.2.6 classification specification—a set of user defined ac-
ceptance criterion that prescribes the radiographic workman-
ship discontinuity class requirements for a specified user
casting service application (see Sections 6 and 7).
3.2.7 graded illustration—a category of discontinuity that is
assigned a severity level.
3.2.8 ungraded illustration—a category of discontinuity
without an assigned severity level.
3.2.9 prorating—assignment of quantity, size and distribu-
tion on a production radiograph in proportion to a similar size
area of a reference radiograph. For example: a production
radiograph covers an area that is smaller than the unit area of
a reference radiograph and the extent of discontinuity on the
applicable reference radiograph is reduced proportionately.
4. Significance and Use
4.1 Graded reference radiographs are intended to provide a
guide enabling recognition of specific casting discontinuity
types and relative severity levels that may be encountered
during typical fabrication processes. Reference radiographs
containing ungraded discontinuities are provided as a guide for
recognition of a specific casting discontinuity type where
severity levels are not needed. These reference radiographs are
intended as a basis from which manufacturers and purchasers
may, by mutual agreement, select particular discontinuity
classes to serve as standards representing minimum levels of
acceptability (see Sections 6 and 7).
4.2 Reference radiographs represented by this standard may
be used, as agreed upon in a purchaser supplier agreement, for
energy levels, thicknesses or both outside the range of this
standard when determined applicable for the casting service
application. Severity levels of similar discontinuity categories
and energy level range of E186 reference radiographs may
alternatively be used, as determined appropriate for the casting
service application, if so agreed upon in the purchaser supplier
agreement (see Note 2 and 5.1).
4.3 Procedures for evaluation of production radiographs
using applicable reference radiographs of this standard are
prescribed in Section 8; however, there may be manufacturing-
purchaser issues involving specific casting service applications
where it may be appropriate to modify or alter such require-
ments. Where such modifications may be appropriate for the
casting application, all such changes shall be specifically
called-out in the purchaser supplier agreement or contractual
document. Section 9 addresses purchaser supplier requisites for
where weld repairs may be required.
5. Method of Preparation
5.1 The original radiographs used to prepare the adjunct
reference radiographs were produced on ASTM Class I or II
film systems by the respective use of 250-kV X-ray, Iridium-
192 and Cobalt-60 sources of radiation. The original radio-
graphs were made with penetrameter sensitivity as determined
by ASTM penetrameters (see Guide E94) of 2-2T. The adjunct
reference radiographs are reproductions prepared to an optical
density of 2.00 to 2.25 and have substantially retained the
contrast of the original radiographs. In preparing these refer-
ence radiographs, the objective was to obtain progressively
graduated severity levels for each graded discontinuity cat-
egory of this standard. Additionally, some overlap of severity
levels may occur for discontinuity categories of this standard
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
4
Available from ASTM Headquarters.
5
Order RRE044601.
6
Order RRE044602.
7
Order RRE044603.
E446 − 14
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3. and similar discontinuity categories of E186 reference radio-
graphs within the same energy level range. For example,
aggregate gas porosity severity level 5 of this standard exceeds
aggregate gas porosity severity level 1 of Reference Radio-
graph E186 (see 6.3).
5.2 Film Deterioration—Radiographic films are subject to
wear and tear from handling and use. The extent to which the
image deteriorates over time is a function of storage
conditions, care in handling and amount of use. Reference
radiograph films are no exception and may exhibit a loss in
image quality over time. The radiographs should therefore be
periodically examined for signs of wear and tear, including
scratches, abrasions, stains, and so forth. Any reference radio-
graphs which show signs of excessive wear and tear which
could influence the interpretation and use of the radiographs
should be replaced.
6. Determination of Radiographic Classification
6.1 For purposes of evaluation of castings, a determination
must be made of the radiographic discontinuity classifications
to be assigned to individual castings or specific areas of
castings. The determination of the applicable radiographic
discontinuity classification shall be based on an evaluation of
the casting applications, design, and service requirements. In
these evaluations, consideration shall be given to such factors
as pressure, temperature, section thickness, applicable design
safety factor (preferably based on stress analysis), vibration,
shock, resistance to corrosion, involvement of penetrating
radiations or radiation products, and involvement of dangerous
gases or liquids.
6.2 For each individual casting or specific area of a casting
to be radiographed, the discontinuity class must be clearly
specified. For example, severity level 2 might be specified for
linear shrinkage, Category Ca, and severity level 3 for gas
porosity, Category A, since the latter are generally much less
deleterious to tensile properties (see Section 7).
6.3 When determining discontinuity severity levels for in-
dividual castings spanning multiple thickness ranges outside
the range of this standard, consideration should be given to the
potential for overlaping severity levels as described in 4.2 and
5.1.
6.4 Production radiographs which are compared to refer-
ence radiographs should have an optical density in the area of
interest in accordance with Guide E94 and a specified mini-
mum radiographic sensitivity (quality level) of 2 % (2-2T).
Other radiographic quality levels or optical densities may be
designated, but then a corresponding change in severity level
for each discontinuity category should be anticipated and hence
specified.
7. Classification Specifications
7.1 The applicable radiographic discontinuity classification
should be designated by the contracting agency in formal
specifications or on drawings and in specific contracts or
orders. The specifications, drawings, contracts, or order should
also designate the sampling plan for the castings to be
radiographed and the extent of radiographic coverage, radio-
graphic practice to be followed (Guide E94), image quality
desired (Note 5) as well as the severity of the acceptable
discontinuity for the graded categories.
NOTE 5—For description of radiographic sensitivity or quality levels,
see Guide E94 and Reference Radiographs E242.
8. Evaluation Procedure
8.1 Compare the production radiographs of the casting
submitted for evaluation with the reference radiographs ex-
posed at an equivalent energy range within the thickness range
of this standard (unless otherwise specified—see Section 4).
8.2 When the severity level of discontinuities in the produc-
tion radiograph being evaluated is equal to or less than the
severity level in the specified reference radiograph, that part of
the casting represented by the production radiograph shall be
acceptable. If the production radiograph shows discontinuities
of greater severity than the reference radiograph, that part of
the casting shall be rejected.
8.3 A unit area on the production radiograph shall be
evaluated to a unit area of like size on the reference radiograph.
Any unit evaluation area that shares a discontinuity with an
adjacent unit evaluation area shall meet the minimum unit area
acceptability requirements within the combined unit area.
When the unit area of interest of a production radiograph is less
than the unit area of the applicable reference radiograph, such
unit area of the production radiograph shall be prorated to the
reference radiographic area.
8.4 When two or more categories of discontinuity are
present in the same production radiograph, the predominating
discontinuites, if unacceptable, shall govern without regard to
the other categories of discontinuity and the casting rejected.
8.5 When two or more categories of discontinuity are
present to an extent equal to the maximum permissible level as
shown in the applicable standards for each category, then that
part of the casting shall be judged unacceptable. When two or
more categories of discontinuity are present in the same
radiograph to an extent less than the maximum permissable
level, as shown in the applicable standards for each category,
the severity shall be evaluated by the overall aggregate
condition. The aggregate condition is defined as the balance of
quantity, size and distribution of the collection of discontinui-
ties and shall not exceed the aggregate condition of the
applicable reference radiograph.
8.6 Reference radiographs are provided showing a variety
of shrinkage discontinuity types. Production radiographs show-
ing shrinkage shall be judged by the most representative
reference radiograph.
8.7 This standard does not specify limiting criteria for a
single size of discontinuity, maximum number of discontinui-
ties per unit area evaluated, specific dimensional spacing
and/or alignment criterion between individual discontinuities
or any other undefined discontinuitiy patterns. Unless other-
wise specified by a purchaser supplier agreement (see Section
4), these discontinuity conditions on production radiographs
shall be evaluated as aggregate conditions as defined in 8.5.
E446 − 14
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4. 8.8 In general, there is no limit as to the extent of acceptable
discontinuities in a casting, provided that no unit evaluation
area throughout the casting contains discontinuities that exceed
the severity of discontinuities in the applicable reference
radiographs.
8.9 Reference radiographs in this standard do not illustrate
elongated or “worm hole” type of gas discontinuities. When
this condition occurs in a production radiograph, it shall be
evaluated by comparison with the most representative refer-
ence radiograph.
8.9.1 When the exposing radiation source has been placed
perpendicular to the length of the gas hole, evaluate the
production radiograph with a shrinkage reference radiograph.
8.9.2 When the exposing radiation source has been placed
diametrically or“into” the diameter of the gas hole, evaluate the
production radiograph with a gas reference radiograph.
8.10 A diffraction mottling pattern can occur on films of
parts and sections where the grain size is large enough to be an
appreciable fraction of the material thickness (Note 6). If
diffraction mottling is suspected, there are a number of ways to
demonstrate its presence. The diffraction mottling pattern
shown in these cases is dependent principally upon the crystal
geometry and the orientation of the crystals to the incident
radiation. Therefore, for a given specimen, any change in this
orientation will affect the diffraction pattern dramatically. This
can be accomplished by a slight, 1 to 5° tilt of the part, with
respect to the radiation beam or simply by shifting the center
line of the radiation beam to a slightly different location from
the first exposure. Indications from any porosity, shrinkage, or
other discontinuity will move only slightly, while any mottling
patterns present will change dramatically. If it is necessary or
desirable to eliminate the mottling, the kV may be raised to
reduce the amount of diffraction radiation. However, caution
should be used so that the kV is not raised to the point that
sensitivity is reduced excessively. If diffraction mottling is
demonstrated to be present on a radiograph, this condition shall
not be considered as prejudicial in evaluating the radiograph.
NOTE 6—Mottling is often associated with thin sections of austenitic
steels, and copper base alloys such as copper nickel, tin bronzes, and
nickel copper.
8.11 Hot tears and cracks exhibited on production radio-
graphs may at times resemble linear type shrinkage. When
doubt exists whether such indications are cracks or tears, or are
linear shrinkage, all surfaces in the area of interest shall be
ground and magnetic particle or liquid penetrant inspected as
applicable. The extent and depth of grinding may require
engineering judgment. If the indication does not appear on the
surface, that indication shall be considered shrinkage.
8.12 The radiographic density of discontinuities in compari-
son with background density is a variable dependent on
technical factors. It shall not be used as a criterion for
acceptance or rejection in comparison with reference radio-
graphs.
9. Weld Repair of Castings
9.1 When radiographic quality castings are repaired by
welding, the reference radiographs to be used in the evaluation
of the repaired sections must be specifically agreed upon
between purchaser and supplier.
9.2 When casting discontinuities are removed for repairs,
only the extent of discontinuity required to meet applicable
reference standards need be removed.
10. Keywords
10.1 discontinuity classification criterion; gamma ray; ref-
erence radiographs; steel castings; x-ray
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E446 − 14
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